When interconnected to the circulatory system of a patient, a heart/lung machine oxygenates, pumps and heats the blood supply of a patient. Oxygen poor blood flows from the patient to the heart/lung machine, where it is oxygenated and heated, and then pumped back to the patient. Essentially, the pump used in a heart/lung machine serves as a temporary heart for the patient. Prior to connection of a patient to a heart/lung machine, it is necessary to prime the pump with blood compatible saline.
In the past, several types of pumps have been used to pump blood through a heart/lung machine. For instance, positive displacement peristaltic pumps and centrifugal pumps have been used for this purpose. Both of these pump types require a relatively large volume of saline for priming.
Applicant's co-pending U.S. patent application Ser. No. 07/529,598, filed on May 29, 1990, discloses an axial flow motor/blood pump. This motor/blood pump requires significantly less saline solution for priming. This axial motor/blood pump also has fewer parts and is less expensive than prior pumps, both of which features are particularly important because blood-contacting medical equipment is thrown away after a single use. Disposing of equipment or components that directly contact the blood reduces the risk of transmitting blood carried diseases or viruses such as the HIV virus which carries acquired immuno-deficiency syndrome ("AIDS").
With this axial flow motor/blood pump, the motor controller and stator are reused, while the pump and its components are thrown away after a single use. The pump includes a housing connected in line with the blood flow path. To connect the pump to the blood flow path, tubes are connected to the ends of the housing. Prior to connection of the tube at one end of the housing, the stator is slid over that end of the housing and then the tube is connected. The tubes and the housing are normally sterilized when packaged by the manufacturer. However, because a nonsterilized piece of equipment, i.e., the stator, is slid over the end of the housing, the assembled motor/blood pump must be sterilized again prior to use. After use, one of the tubes is disconnected from the housing, and the stator is slidably removed from the housing for reuse, while the housing and tubing are discarded.
Although this axial flow motor/blood pump has proved to be advantageous over prior blood pumps, applicant has recognized that a further advantage could be achieved if the reusable components of the motor/blood pump could be connected/disconnected to/from the disposable components without interrupting the blood flow path. This would eliminate the need to resterilize components prior to use, and it would also reduce the amount of direct blood contact required of hospital personnel when disconnecting a patient from a heart/lung machine.